EP1548760A2 - Poudre magnétique en nitride de fer et procédé de fabrication associé - Google Patents

Poudre magnétique en nitride de fer et procédé de fabrication associé Download PDF

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EP1548760A2
EP1548760A2 EP04027437A EP04027437A EP1548760A2 EP 1548760 A2 EP1548760 A2 EP 1548760A2 EP 04027437 A EP04027437 A EP 04027437A EP 04027437 A EP04027437 A EP 04027437A EP 1548760 A2 EP1548760 A2 EP 1548760A2
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Prior art keywords
magnetic powder
iron nitride
magnetic
nitride magnetic
powder
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German (de)
English (en)
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EP1548760A3 (fr
Inventor
Kenji Dowa Mining Co. Ltd. Masada
Takafumi Dowa Mining Co. Ltd. Amino
Akira Dowa Mining Co. Ltd. Nagatomi
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Dowa Electronics Materials Co Ltd
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Dowa Electronics Materials Co Ltd
Dowa Mining Co Ltd
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Publication of EP1548760A3 publication Critical patent/EP1548760A3/fr
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/0615—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with transition metals other than titanium, zirconium or hafnium
    • C01B21/0622—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with transition metals other than titanium, zirconium or hafnium with iron, cobalt or nickel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/16—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on nitrides
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
    • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
    • G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
    • G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/065—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder obtained by a reduction
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/32—Thermal properties
    • C01P2006/37—Stability against thermal decomposition
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/42—Magnetic properties
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12181—Composite powder [e.g., coated, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
    • Y10T428/2991—Coated
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
    • Y10T428/2991—Coated
    • Y10T428/2993—Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
    • Y10T428/2991—Coated
    • Y10T428/2993—Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
    • Y10T428/2995—Silane, siloxane or silicone coating

Definitions

  • This invention relates to an iron nitride magnetic powder suitable for constituting the magnetic layer of a high recording density medium and a method of producing the powder.
  • a magnetic powder used in a magnetic recording medium enabling high density recording requires high coercive force (Hc) in order to maintain magnetism in the high-density medium and to ensure the output.
  • Hc coercive force
  • SFD Switching Field Distribution
  • JP2000-277311A (Ref. No. 1) describes an iron nitride magnetic material of large specific surface area that exhibits high coercive force Hc and high saturation magnetization ⁇ s, and teaches that excellent magnetic properties can be achieved irrespective of shape owing to a synergistic effect between the crystal magnetic anisotropy of an Fe 16 N 2 phase and powder specific surface area enlargement.
  • JP2001-176715A (Ref. No. 2) describes a low-cost magnetic material exhibiting high saturation magnetization ⁇ s as a magnetic powder in which 10 - 90% of Fe 16 N 2 phase is generated and particularly teaches that the saturation magnetization is maximum when the Fe 16 N 2 phase generation rate is 60%.
  • W0 03/079332 A1 proposes rare earth element-iron-boron system, rare earth element-iron system and rare earth element-iron nitride system magnetic powders composed of substantially spherical or ellipsoid particles and states that a tape medium produced using such a powder has excellent properties, that, in particular, the rare earth element-iron nitride system magnetic powder whose main phase is Fe 16 N 2 is high in saturation magnetism despite being composed of 20 nm particles and also good storage stability because it has a high coercive force of 200 KA/m or greater and a small BET specific surface area, and that use of this rare earth element-iron nitride system magnetic powder enables a dramatic increase in the recording density of a coating-type magnetic recording medium.
  • This rare earth element-iron nitride system magnetic powder is produced by ammonia nitriding in which rare earth element-iron system magnetic powder obtained by reducing magnetite particles with a surface-adhered rare earth element is nitrided using ammonia gas.
  • Ref. No. 3 is said to enable replacement of part of the iron in the rare earth element-iron nitride with another transition metal element, it is pointed out that a long time is required for the nitriding reaction when a large amount of cobalt is added.
  • JP-Hei11-340023A (Ref. No. 4) discloses the basic invention to obtain an iron-nitride magnetic powder of Fe 16 N 2 phase by a low temperature nitriding method using ammonia gas.
  • Ref. Nos. 1 - 3 say that a fine magnetic powder with good magnetic properties is obtained when an Fe 16 N 2 phase having large crystal magnetic anisotropy is generated, they do not say that a higher ratio of Fe 16 N 2 phase is always better.
  • Ref. No. 2 states that the highest ⁇ s is obtained when the Fe 16 N 2 phase ratio is about 60%.
  • Ref. No. 3 says that the core portion need not be entirely Fe 16 N 2 phase but can be a mixed phase including ⁇ -Fe and also that the desired coercive force can be easily set by regulating the nitriding conditions.
  • a magnetic powder has a broad bulk switching field distribution means that high and low Hc particles are intermixed. Therefore, when such a magnetic powder is used in a coating material for preparing a tape to be used as a high-density recording medium, noise readily occurs. Moreover, when low Hc components are present, such particles are apt to experience erasure of recorded content because they cannot maintain magnetism owing to thermal fluctuation, so that a reliability problem arises. Therefore, a magnetic powder that is substantially Fe 16 N 2 phase with no mixed in ⁇ -Fe phase, Fe 4 N phase or the like is preferable as a magnetic powder for a high-recording density magnetic medium.
  • JP-Hei-11-340023A (Ref. No. 4) sets out a method of producing Fe 16 N 2 phase particles by low-temperature nitriding, it is silent regarding the crystal state, coercive force Hc and switching field distribution of the product.
  • the rare earth element-iron system magnetic powder described in Ref. No. 3 achieves ⁇ s of 12.6% in a 20 nm average particle diameter magnetic powder comprising a mixture of Fe 16 N 2 and ⁇ -Fe phases and containing 5.3 at.% of Y, for example.
  • this oxidation resistance probably needs to be increased to a still higher level because specific surface area increases markedly when further particle refinement is carried out.
  • An object of the present invention is therefore to provide an Fe 16 N 2 system iron nitride powder that achieves excellent magnetic properties enabling use in a high-recording density magnetic medium, particularly high Hc and low BSFD, together with good oxidation resistance.
  • an iron nitride magnetic powder composed substantially of Fe 16 N 2 can be stably produced by allowing a nitriding reaction of Fe particles with a nitrogen-containing gas, typically ammonia gas, for producing nitrided particles of primarily Fe 16 N 2 phase to proceed under an increased pressure of 0.1 MPa or greater, preferably 0.3 MPa or greater. That is, it was found that conducting the nitriding reaction under increased pressure suppresses generation of other phases such as ⁇ -Fe phase and Fe 4 N phase to enable production of a powder composed substantially of Fe 16 N 2 .
  • a nitrogen-containing gas typically ammonia gas
  • the present invention can therefore provide an iron nitride magnetic powder characterized in that its coercive force Hc is 200 KA/m or greater and bulk switching field distribution (BSFD) is 2 or less.
  • This iron nitride magnetic powder is preferably composed of iron nitride particles 80% or more of which are Fe 16 N 2 phase as determined by XRD peak integration and 15% or less of which are of Hc of 120 KA/m or less in the bulk switching field distribution.
  • the average particle diameter thereof is preferably 50 nm or less.
  • the magnetic powder of the present invention is a high Hc, low SFD fine powder substantially composed of Fe 16 N 2 that can be applied to a coating-type magnetic recording medium to achieve a magnetic recording medium having high recording density. It is therefore capable of enhancing data storage capacity in response to expected increases in the volume of data requiring backup.
  • the present invention achieves production of an iron nitride magnetic powder that exhibits both high Hc and low BSFD by setting the pressure during nitriding at 0.1 MPa or greater, preferably 0.3 MPa or greater.
  • the obtained magnetic powder of primarily Fe 16 N 2 phase In order for the obtained magnetic powder of primarily Fe 16 N 2 phase to exhibit Hc of 120 KA/m or greater and BSFD of 2 or less, it should consist of 80% or more, preferably 90% or more, of Fe 16 N 2 phase as determined by XRD peak integration.
  • Fe ( ⁇ -Fe) particles As the starting material subjected to nitriding under increased pressure can be used Fe ( ⁇ -Fe) particles (powder).
  • the used Fe powder can be one obtained by reducing or decomposing goethite, hematite, magnetite, wustite, ⁇ -Fe, carbonyl iron, iron acetylacetonate or the like.
  • the particular shape is not especially limited and can be any of acicular, spindle shape, spherical, ellipsoid or the like, but the average particle diameter is preferably 50 nm or less, more preferably 20 nm or less.
  • Fe particles of a diameter of 50 nm or less enables production of a magnetic powder composed of Fe 16 N 2 single phase particles of a diameter of 50 nm or less, which powder is a magnetic material suitable for short-wavelength recording. Moreover, the fine particles of a diameter of 50 nm or less make it possible to obtain a high-recording density magnetic medium that is excellent in surface smoothness and low in noise.
  • the particles may have a sinter preventing agent incorporated in solid solution therein or adhered to the surface thereof in an amount that does not markedly inhibit nitriding.
  • Usable sinter preventing agents include ones that contain Al, Si, Cr, V, Mn, Mo, Ni, P, B, Zr, a rare earth element (defined as including Y) or the like.
  • an Al-system agent that readily enters solid solution is suitable, and when magnetite or the like is used, an Si-system agent that readily enters solid solution or adheres to the particles is suitable.
  • Al and Si have a nitriding promoting effect, their addition is still more preferable from the viewpoint of further enhancing magnetic properties and improving productivity.
  • the combination of Al and a rare earth element (defined as including Y) or the combination of Si and a rare earth element (defined as including Y) can be preferably adopted to enhance the above effects.
  • Al content can be in the range of 5-30 at.% based on Fe
  • Si content can be in the range of 1-10 at.% based on Fe
  • a rare earth element (defined as including Y) can be in the range of 0.5-10 at.% based on Fe. If their contents are lower than each lower limit above, it is hard to obtain the sinter preventing effect, and when their contents are higher than each upper limit above, non-magnetic components are excessively increased thereby to render the saturation magnetization insufficient.
  • the oxidation resistance of the iron nitride magnetic powder comprising Fe 16 N 2 phase can be improved by adding one or both of Co and Ni to the starting material.
  • the total amount Co and/or Ni added expressed in atomic percent based on Fe is preferably 0.1 - 30 at.%, more preferably 10 - 30 at.%. When the total added amount is less than 0.1 at.%, no oxidation resistance improvement effect is observed, and when it exceeds 30 at.%, a long period is required for the nitriding reaction, which is undesirable. Addition of one or both of Co and Ni in a total amount of 0.1 - 30 at.%, preferably 10 - 30 at.%, is appropriate from the aspects of both oxidation resistance and nitriding reaction.
  • the present invention enables production of an iron nitride magnetic powder whose ⁇ s, an index of oxidation resistance, is 15% or less.
  • the reducing agent used in the reduction treatment for obtaining ⁇ -Fe is not particularly defined and can be of any type capable of decomposing or reducing the starting material powder to ⁇ -Fe.
  • hydrogen H 2
  • insufficient reduction that results in residual oxygen is undesirable because it greatly slows the nitriding speed.
  • An excessively high temperature during reduction causes sintering between the particles, thereby increasing the average particle diameter and degrading dispersibility.
  • the reduction should therefore be conducted at a temperature of 500 °C or lower, for example, at a temperature in the range of 300 - 500 °C.
  • the nitriding of Fe particles (powder) in accordance with the present invention is preferably carried out using a nitrogen-containing gas, typically ammonia gas, under an increased pressure of 0.1 MPa or greater, preferably 0.3 MPa or greater, at a temperature of 200 °C or lower for between several hours and several tens of hours.
  • the pressurization method is not particularly defined.
  • One convenient method is to blow ammonia gas or a mixed gas containing ammonia gas into a furnace capable of withstanding pressure increase and controlling the pressure on the upstream and downstream sides of the furnace to regulate the pressure in the furnace.
  • the amount of oxygen in the gas passed through the furnace is preferably less than a few ppm.
  • the present invention can produce an iron nitride magnetic powder substantially composed of Fe 16 N 2 phase and the magnetic powder obtained is suitable for use as a magnetic material for a high-density magnetic recording medium.
  • the present invention can produce a magnetic powder substantially composed of Fe 16 N 2 phase, which has an average particle diameter of 50 nm or less, exhibits Hc of 120 KA/m or greater and BSFD of 2 or less, and has a ratio below Hc 120 KA/m in BSFD of 15% or less.
  • the magnetic powder can serve as a magnetic material for a high-density magnetic recording medium having no problem of thermal fluctuation and no problem of noise generation when made into a tape.
  • the magnetic powder is one that contains one or both of Co and Ni, the resulting excellent oxidation resistance gives it high practical value.
  • a BSFD exceeding 2 i.e., a wide Hc distribution in the powder that makes the ratio of high Hc components and low Hc components large, causes noise in a tape produced using the magnetic powder, while low Hc magnetic powder is liable to experience erasure of recorded content owing to thermal fluctuation, so that a reliability problem arises.
  • the BSFD is therefore preferably 2 or less.
  • Magnetic powder 0.500 g, was weighed out and placed in a pot (inside diameter: 45 mm, depth: 13 mm) and allowed to stand for 10 min. with the cover open.
  • 0.700 mL of a vehicle mixed solution of vinyl chloride resin MR-110 (22 wt%), cyclohexanone (38.7 wt%), acetylacetone (0.3 wt%), n-butyl stearate (0.3 wt%) and methyl ethyl ketone (MEK, 38.7%) was added to the pot using a micropipette.
  • a steel ball (2 ⁇ ) 30 g and ten nylon balls (8 ⁇ ) were immediately added to the pot and the pot was covered and allowed to stand for 10 min.
  • the pot was then set in a centrifugal ball mill (Fritsch P-6) and gradually raised to a final rotating speed of 600 rpm, at which dispersion was continued for 60 min.
  • the centrifugal ball mill was stopped and the pot removed.
  • the pot was added with 1.800 mL of a liquid adjuster prepared in advance by mixing MEK and toluene at a ratio of 1 : 1.
  • the pot was again set in the centrifugal ball mill and rotated at 600 rpm for 5 minutes. This completed the dispersion.
  • the cover of the pot was opened and the nylon balls removed.
  • the coating material, together with the steel ball, was placed in an applicator (55 ⁇ m) and coated onto a support film (15 ⁇ m polyethylene film marketed by Toray Industries under the product designation 15C-B500).
  • the coated film was promptly placed at the center of the coil of a 5.5 kG magnetic orientation device to orient its magnetic field, and then dried.
  • starting material a powder composed of 27 nm average diameter magnetite particles having a surface layer of Si and Y oxides (Si and Y content expressed as atomic percent based on Fe of 4.7 at.% and 1.0 at.%, respectively).
  • the powder was placed in a furnace, heated, and reduced in a stream of hydrogen gas at 500 °C for one hour. It was then cooled to 100 °C, at which temperature the gas of the gas stream was changed from hydrogen to ammonia, and thereafter heated to 165 °C. At this temperature, the outlet pressure of the discharge gas was regulated to put the furnace under a controlled pressurized condition of 0.1 MPa. Nitriding was conducted for 11 hours under this pressurized condition.
  • the outlet pressure of the discharge gas was returned to atmospheric pressure to discontinue the pressurization, whereafter the temperature was lowered to 80 °C and the gas of the gas stream was changed to nitrogen gas to which was added a small amount of air so as to impart an oxygen concentration of 0.01 - 2 vol.% and subject the surface of the powder under treatment to slow oxidation. The powder was then taken out into the air.
  • the powder obtained had an average particle diameter of 25 nm and a BET specific surface area of 43 m 2 /g.
  • the powder oxidation resistance ⁇ s was 19.8% and the ratio below Hc 120 KAm in the BSFD was 11.6%.
  • FIG. 1 shows the hysteresis curve and derivative curve obtained for the iron nitride magnetic powder of this example.
  • Example 1 was repeated except that the outlet pressure of the discharge gas was regulated to put the furnace under a controlled pressurized condition of 0.3 MPa.
  • the powder obtained had an average particle diameter of 25 nm and a BET specific surface area of 44 m 2 /g.
  • the powder oxidation resistance ⁇ s was 23.7% and the ratio below Hc 120 KAm in the BSFD was 9.3%.
  • Example 1 was repeated except that the starting material used was 20 nm average diameter goethite particles containing Al and Y as sinter preventing agents at atomic percents based on Fe of 9.4 at.% and 1.9 at.%, respectively.
  • the powder obtained had an average particle diameter of 15 nm and a BET specific surface area of 69 m 2 /g.
  • the powder oxidation resistance ⁇ s was 35.3% and the ratio below Hc 120 KAm in the BSFD was 13.2%.
  • Example 1 was repeated except that the starting material used was 20 nm average diameter goethite particles containing Co at an atomic percent based on Fe of 3.0 at.% (and also containing Al and Y as sinter preventing agents at 9.1 at.% and 1.0 at.%, respectively).
  • the powder obtained had an average particle diameter of 15 nm and a BET specific surface area of 66 m 2 /g.
  • the powder oxidation resistance ⁇ s was 14.5% and the ratio below Hc 120 KAm in the BSFD was 13.5%.
  • Example 1 was repeated except that the starting material used was 25 nm average diameter goethite particles containing Co at an atomic percent based on Fe of 20 at.% (and also containing Al and Y as sinter preventing agents at 9.1 at.% and 1.0 at.%, respectively).
  • the powder obtained had an average particle diameter of 21 nm and a BET specific surface area of 55 m 2 /g.
  • the powder oxidation resistance ⁇ s was 8.7% and the ratio below Hc 120 KAm in the BSFD was 11.8%.
  • Example 1 was repeated except that the starting material used was 25 nm average diameter goethite particles containing Ni at an atomic percent based on Fe of 10 at.% (and also containing Al and Y as sinter preventing agents at 9.1 at.% and 1.0 at.%, respectively).
  • the powder obtained had an average particle diameter of 20 nm and a BET specific surface area of 57 m 2 /g.
  • the powder oxidation resistance ⁇ s was 9.0% and the ratio below Hc 120 KAm in the BSFD was 12.1%.
  • Example 1 was repeated except that outlet pressure of the discharge gas was released into the atmosphere so as not to pressurize the furnace interior (furnace pressure was not higher than 0.01 MPa).
  • the powder obtained had an average particle diameter of 25 nm and a BET specific surface area of 45 m 2 /g.
  • the powder oxidation resistance ⁇ s was 25.2% and the ratio below Hc 120 KAm in the BSFD was 21.1%.
  • FIG. 2 shows the hysteresis curve and derivative curve obtained for the magnetic powder of this example.
  • the iron nitride magnetic powder obtained in Example 1 was used to fabricate a magnetic test tape having a double-layer structure composed of a magnetic layer and a nonmagnetic layer. Magnetic conversion measurement and storage stability evaluation were carried out.
  • 100 parts by weight of the iron nitride magnetic powder were blended with the materials set out below in the indicated number of parts by weight.
  • 85 parts by weight of nonmagnetic powder were blended with the materials set out below in the indicated number of parts by weight. Both blends were kneaded and dispersed using a kneader and a sand grinder.
  • the obtained coating material for magnetic layer formation and coating material for nonmagnetic layer (underlayer) formation were applied onto a base film composed of an aramid support to obtain the desired underlayer thickness of 2.0 ⁇ m and a magnetic layer thickness of 0.20 ⁇ m.
  • the magnetic layer was oriented while still damp by exposure to a magnetic field, whereafter drying and calendering were conducted to obtain a double-layer structure magnetic tape.
  • Magnetic coating material composition Iron nitride magnetic powder 100 parts by weight Carbon black 5 parts by weight Alumina 3 parts by weight Vinyl chloride resin (MR110) 15 parts by weight Urethane resin (UR8200) 15 parts by weight Stearic acid 1 part by weight Acetylacetone 1 part by weight Methyl ethyl ketone 190 parts by weight Cyclohexanone 80 parts by weight Toluene 110 parts by weight Nonmagnetic coating material composition Nonmagnetic powder ( ⁇ -Fe2O3) 85 parts by weight Carbon black 20 parts by weight Alumina 3 parts by weight Vinyl chloride resin (MR110) 15 parts by weight Urethane resin (UR8200) 15 parts by weight Methyl ethyl ketone 190 parts by weight Cyclohexanone 80 parts by weight Toluene 110 parts by weight
  • the magnetic properties, i.e., the magnetic conversion properties (C/N, output), of the obtained magnetic tape were measured.
  • C/N ratio measurement a drum tester was attached to the recording head and a digital signal was recorded at a recording wavelength of 0.35 ⁇ m. At this time, an MR head was used to measure the reproduced signal and noise was measured as demodulation noise.
  • the output and C/N in the case of using the iron nitride magnetic powder of Comparative Example 1 was defined as 0 dB. The results of the evaluations are shown in Table 2.
  • Example 7 was repeated except that the iron nitride magnetic powder obtained in Examples 2 to 6 were used. The same evaluations as in Example 7 were carried out. The results are shown in Table 2.
  • Example 7 was repeated except that the iron nitride magnetic powder obtained in Comparative Example 1 was used. The same evaluations as in Example 7 were carried out. The results are shown in Table 2. Magnetic powder used Magnetic conversion measurements Output (dB) N(dB) C/N (dB) Example 7 Example 1 1.0 -0.8 1.8 Example 8 Example 2 1.3 -1.0 2.3 Example 9 Example 3 0.6 -1.8 2.4 Example 10 Example 4 0.4 -1.6 2.0 Example 11 Example 5 0.9 -1.0 1.9 Example 12 Example 6 0.6 -1.1 1.7 Comparative Example 2 Comparative Example 1 0 0 0 0 0

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EP1675135A1 (fr) * 2004-12-21 2006-06-28 Dowa Mining Co., Ltd. Poudre magnétique en nitride de fer ayant une haute stabilité au stockage
EP1748450A1 (fr) * 2005-07-28 2007-01-31 Dowa Mining Co., Ltd. Poudre magnétique pour supports à faible bruit
EP1577907A3 (fr) * 2004-03-17 2007-12-26 DOWA Electronics Materials Co., Ltd. Poudre de nitride de fer et procédé de production associé
EP2031607A1 (fr) * 2006-06-14 2009-03-04 DOWA Electronics Materials Co., Ltd. Poudre magnetique a base de nitrure de fer, son processus de fabrication, et support d'enregistrement magnétique
CN102214509A (zh) * 2010-04-12 2011-10-12 北京有色金属研究总院 一种（FeCo）N微波吸收材料及其制备方法
US9715957B2 (en) 2013-02-07 2017-07-25 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
US9994949B2 (en) 2014-06-30 2018-06-12 Regents Of The University Of Minnesota Applied magnetic field synthesis and processing of iron nitride magnetic materials
US10002694B2 (en) 2014-08-08 2018-06-19 Regents Of The University Of Minnesota Inductor including alpha″-Fe16Z2 or alpha″-Fe16(NxZ1-x)2, where Z includes at least one of C, B, or O
US10068689B2 (en) 2011-08-17 2018-09-04 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
US10072356B2 (en) 2014-08-08 2018-09-11 Regents Of The University Of Minnesota Magnetic material including α″-Fe16(NxZ1-x)2 or a mixture of α″-Fe16Z2 and α″-Fe16N2, where Z includes at least one of C, B, or O
EP2028255B1 (fr) * 2007-08-02 2019-06-12 Petróleo Brasileiro S.A. Petrobras Procédé pour obtenir un composé intermétallique et son utilisation dans des huiles lubrifiantes
US10358716B2 (en) 2014-08-08 2019-07-23 Regents Of The University Of Minnesota Forming iron nitride hard magnetic materials using chemical vapor deposition or liquid phase epitaxy
US10504640B2 (en) 2013-06-27 2019-12-10 Regents Of The University Of Minnesota Iron nitride materials and magnets including iron nitride materials
US10573439B2 (en) 2014-08-08 2020-02-25 Regents Of The University Of Minnesota Multilayer iron nitride hard magnetic materials
US11195644B2 (en) 2014-03-28 2021-12-07 Regents Of The University Of Minnesota Iron nitride magnetic material including coated nanoparticles

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JP4070147B1 (ja) * 2006-09-27 2008-04-02 日立マクセル株式会社 磁気記録媒体
US8535634B2 (en) * 2007-05-04 2013-09-17 Advanced Materials Corporation Iron nitride powders for use in magnetic, electromagnetic, and microelectronic devices
JP5769223B2 (ja) * 2009-10-22 2015-08-26 戸田工業株式会社 強磁性粒子粉末及びその製造法、異方性磁石及びボンド磁石
JP5822188B2 (ja) * 2010-09-24 2015-11-24 戸田工業株式会社 強磁性粒子粉末及びその製造法、異方性磁石及びボンド磁石
JP5831866B2 (ja) * 2011-01-21 2015-12-09 戸田工業株式会社 強磁性粒子粉末及びその製造方法、並びに異方性磁石、ボンド磁石及び圧粉磁石
JP5858419B2 (ja) * 2011-04-27 2016-02-10 戸田工業株式会社 強磁性粒子粉末の製造方法、異方性磁石、ボンド磁石及び圧粉磁石
CN103145106B (zh) * 2013-01-29 2015-07-01 辽宁科技大学 一种氮化铁纳米粉体的制备方法及其高压气固反应床
CN103101892B (zh) * 2013-03-08 2013-10-23 山东大学 一种无需氨气的碳包覆氮化铁纳米粉末的制备方法
JP6380736B2 (ja) * 2013-06-12 2018-08-29 Tdk株式会社 窒化鉄系磁性粉及びそれを用いた磁石
US9822006B2 (en) * 2015-04-09 2017-11-21 The Boeing Company Method to form Fe16N2
CN106057392B (zh) * 2016-06-26 2017-11-07 中国计量大学 α‑Fe/γ′‑Fe4N软磁复合材料的低温原位制备方法
CN106086776B (zh) * 2016-06-26 2018-06-01 中国计量大学 一种氮化铁磁粉的低温等离子氮化制备方法
CN112038082A (zh) * 2020-08-28 2020-12-04 常州古金磁性材料科技有限公司 使用高压氮化的方法制备铁氮磁性材料的方法
CN112735721B (zh) * 2020-12-21 2022-05-27 横店集团东磁股份有限公司 一种高频低损耗复合软磁材料及其制备方法和用途

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Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1577907A3 (fr) * 2004-03-17 2007-12-26 DOWA Electronics Materials Co., Ltd. Poudre de nitride de fer et procédé de production associé
EP1675135A1 (fr) * 2004-12-21 2006-06-28 Dowa Mining Co., Ltd. Poudre magnétique en nitride de fer ayant une haute stabilité au stockage
EP1748450A1 (fr) * 2005-07-28 2007-01-31 Dowa Mining Co., Ltd. Poudre magnétique pour supports à faible bruit
EP2031607A1 (fr) * 2006-06-14 2009-03-04 DOWA Electronics Materials Co., Ltd. Poudre magnetique a base de nitrure de fer, son processus de fabrication, et support d'enregistrement magnétique
EP2031607A4 (fr) * 2006-06-14 2009-06-10 Dowa Electronics Materials Co Poudre magnetique a base de nitrure de fer, son processus de fabrication, et support d'enregistrement magnétique
EP2028255B1 (fr) * 2007-08-02 2019-06-12 Petróleo Brasileiro S.A. Petrobras Procédé pour obtenir un composé intermétallique et son utilisation dans des huiles lubrifiantes
CN102214509A (zh) * 2010-04-12 2011-10-12 北京有色金属研究总院 一种（FeCo）N微波吸收材料及其制备方法
CN102214509B (zh) * 2010-04-12 2013-03-20 北京有色金属研究总院 一种（FeCo）N微波吸收材料及其制备方法
US10068689B2 (en) 2011-08-17 2018-09-04 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
US11742117B2 (en) 2011-08-17 2023-08-29 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
US11217371B2 (en) 2013-02-07 2022-01-04 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
US9715957B2 (en) 2013-02-07 2017-07-25 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
US10692635B2 (en) 2013-02-07 2020-06-23 Regents Of The University Of Minnesota Iron nitride permanent magnet and technique for forming iron nitride permanent magnet
US10504640B2 (en) 2013-06-27 2019-12-10 Regents Of The University Of Minnesota Iron nitride materials and magnets including iron nitride materials
US11195644B2 (en) 2014-03-28 2021-12-07 Regents Of The University Of Minnesota Iron nitride magnetic material including coated nanoparticles
US10961615B2 (en) 2014-06-30 2021-03-30 Regents Of The University Of Minnesota Applied magnetic field synthesis and processing of iron nitride magnetic materials
US9994949B2 (en) 2014-06-30 2018-06-12 Regents Of The University Of Minnesota Applied magnetic field synthesis and processing of iron nitride magnetic materials
US10573439B2 (en) 2014-08-08 2020-02-25 Regents Of The University Of Minnesota Multilayer iron nitride hard magnetic materials
US10358716B2 (en) 2014-08-08 2019-07-23 Regents Of The University Of Minnesota Forming iron nitride hard magnetic materials using chemical vapor deposition or liquid phase epitaxy
US10002694B2 (en) 2014-08-08 2018-06-19 Regents Of The University Of Minnesota Inductor including alpha″-Fe16Z2 or alpha″-Fe16(NxZ1-x)2, where Z includes at least one of C, B, or O
US10072356B2 (en) 2014-08-08 2018-09-11 Regents Of The University Of Minnesota Magnetic material including α″-Fe16(NxZ1-x)2 or a mixture of α″-Fe16Z2 and α″-Fe16N2, where Z includes at least one of C, B, or O
US11214862B2 (en) 2014-08-08 2022-01-04 Regents Of The University Of Minnesota Forming iron nitride hard magnetic materials using chemical vapor deposition or liquid phase epitaxy

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